Nearest neighbour
Tau Ceti
Sun-like star 12 ly away — three confirmed planets, with the outermost (h) in the habitable zone.
- Planets
- 3
- Distance
- 11.8 ly
- Host
- G-type
About Tau Ceti
Discovery
Tau Ceti has been a target of radial-velocity searches for decades; multiple planet candidates have been claimed (Tuomi et al. 2013, Feng et al. 2017) around this naked-eye G8V star just 11.9 light-years away.
Why it matters
Tau Ceti is the closest single Sun-like star — a long-standing prime target in the search for Earth analogs, and a setting for everything from Frank Drake's Project Ozma to modern radial-velocity surveys.
Current research
The system's planet candidates remain controversial — a 2025 analysis flagged the inner detections for revision — and disentangling planets from stellar activity is the ongoing challenge.
Comparable to
The nearest Sun-like star — a slightly cooler, older twin of our own, with planet candidates threading the inner and outer habitable zone.
System geometry
At a glance
- Hostname
- tau Cet
- Spectral type
- G8.5V
- Distance
- 11.8 ly · 3.60 pc
- Stellar mass
- 0.78 M☉
- Stellar radius
- 0.83 R☉
- Luminosity
- 0.495 L☉
- Effective temp
- 5310 K
- Confirmed planets
- 3
- Habitable zone
- 0.668 – 0.964 AU
Top-down orbital diagram
Orbits to scale within this system. Dashed green = habitable-zone edges.
Planet positions are illustrative (evenly spaced in phase). For live motion see the 3D scene.
The planets
3 confirmed.
Rocky world
tau Cet g
- Orbit
- 0.133 AU
- Period
- 20.00 days
- Radius
- 1.18 R⊕
- Mass
- 1.75 M⊕
- Eq. temperature
- —
- Eccentricity
- 0.060
- Discovered
- 2017 · Radial Velocity
Rocky world
tau Cet h
- Orbit
- 0.243 AU
- Period
- 49.41 days
- Radius
- 1.19 R⊕
- Mass
- 1.83 M⊕
- Eq. temperature
- —
- Eccentricity
- 0.230
- Discovered
- 2017 · Radial Velocity
Sub-Neptune
tau Cet f
- Orbit
- 1.334 AU
- Period
- 636.13 days
- Radius
- 1.81 R⊕
- Mass
- 3.93 M⊕
- Eq. temperature
- —
- Eccentricity
- 0.160
- Discovered
- 2017 · Radial Velocity
Compared to our Solar System
Each row shows the closest Solar-System analog by radius (log-space). Earth is pinned at the bottom as the constant frame of reference.
| Planet | Radius (R⊕) | Mass (M⊕) | Orbit (AU) | Period (days) | Eq temp (K) | Solar analog |
|---|---|---|---|---|---|---|
| tau Cet g | 1.18 | 1.75 | 0.133 | 20.00 | — | Earth |
| tau Cet h | 1.19 | 1.83 | 0.243 | 49.41 | — | Earth |
| tau Cet f | 1.81 | 3.93 | 1.334 | 636.13 | — | Earth |
| Earth (reference) | 1.00 | 1.00 | 1.000 | 365.25 | 255 | — |
Research status
◇ JWST observation status
No JWST programs are currently targeting planets in this system. The system may be observed in future cycles or by upcoming missions (Ariel, HWO, Roman).
Discovery timeline
- 2017
3 planets: g, h, f
via Radial Velocity
If you liked this
Other systems in the same theme:
Barnard's Star
4 planets · 6.0 ly · M3.5-4 V
Second-closest star system; planet candidates announced 2024 after decades of false starts.
Ross 128
1 planets · 11.0 ly · M4
A quiet red dwarf 11 ly away with a temperate Earth-mass planet.
Wolf 1061
3 planets · 14.0 ly · M3.5
14 ly away — three planets, the middle one in the habitable zone.
Related reading
Articles mentioning Tau Ceti:
Experience it
See Tau Ceti in interactive 3D
Fly through the system, click any planet, watch orbits play out at 100× speed.
▶ Launch 3D scene